A description will be given to a conventional art taking a cannibalizing machine with an ultra-long attachment used in cannibalizing of a high building as an example.
A base machine A of the above cannibalizing machine is formed by a crawler type lower traveling body 1 and an upper rotating body 2 mounted on the lower traveling body 1 rotatably around a vertical axis as shown in FIG. 9.
A working attachment B provided with a long boom 3 is attached to a front section of the base machine A.
The boom 3 of the working attachment B is formed by connecting a first boom 4, a second boom 5, a third boom 6 and a fourth boom 7 in order from the bottom in which the neighboring booms are connected relatively rotatably around a horizontal axis.
In the boom 3, a lower end of the first boom 4 is attached to the upper rotating body 2 of the base machine A.
A first boom cylinder 8 for raising and lowering the first boom 4 (the entire boom) is provided between the upper rotating body 2 and the first boom 4, a second boom cylinder 9 for raising and lowering the second boom 5 is provided between a front end of the first boom 4 and the second boom 5, a third boom cylinder 10 for raising and lowering the third boom 6 is provided between the second boom 5 and the third boom 6, and a fourth boom cylinder 11 for raising and lowering the fourth boom 7 is provided between the third boom 6 and the fourth boom 7. The cylinders are respectively provided on the lower surface side of the booms.
The entire boom 3 is raised and lowered by the respective boom cylinders 8 to 11, and a bending and stretching action is performed taking connection parts of the respective booms as joints as shown by a broken line in FIG. 9.
In FIG. 9, the reference numeral 12 denotes an openable compression crushing device provided in a front end of the boom 3 (a front end of the fourth boom 7), and the reference numeral 13 denotes a cylinder for compression crushing device adapted to rotate the compression crushing device 12 around the horizontal axis in the up and down direction.
In the case of the above long boom 3, the respective booms 4, 6 and 7 except the short second boom 5 exceed length and weight limitation at the time of transportation as one bloc. Therefore, the respective booms 4, 6 and 7 are divided into a plurality of boom sections, transported and assembled on site.
For example, the first boom 4 is divided into four boom sections Bs of a first (base) boom section, a second boom section, a third boom section and a fourth boom section. Ends thereof opposing to each other are connected to each other by pins.
FIG. 10 shows a state that both the first and second boom sections Bs are connected to each other by pins 14 on both the upper and lower sides.
As mentioned above, a pin connection device for connecting left and right connection portions to each other by separate pins within a narrow clearance of boom width shown in Patent Document 1 is known.
In the above known technique, a pair of hydraulic cylinders are arranged in series having a common piston rod. By performing a stroke operation of cylinder tubes serving as pins in the opposite direction at the same time, both the pins are inserted into and removed from pin holes.
However in the above known technique, since the common piston rod of both the cylinders is supported in a middle part, the entire length of the device is long. Therefore, in the case where the boom width is narrow (a clearance between connection portions on the both sides is narrow), it is difficult to install the device.
Therefore, the following pin connection device is proposed.
As shown in FIGS. 11 and 12, first brackets 15 and 16 serving as a first connection portion are provided on one of the left and right sides of ends of two members (such as both the boom sections Bs in FIG. 10) to be connected to each other. On the other side, second brackets 17 and 18 serving as a second connection portion are provided. First pin holes 19 are provided in the first brackets 15 and 16 and second pin holes 20 are provided in the second brackets 17 and 18.
It should be noted that the figure shows the case where a pair of first brackets 16 on the inside and the outside and a pair of second brackets 18 on the inside and the outside are provided with a small clearance inbetween. However, as a matter of convenience, the brackets 16 and 18 only indicate the brackets on the inside (denoted by the reference numerals 16 and 18 in FIG. 11) in the following description.
The first brackets 15 and 16 and the second brackets 17 and 18 are arranged in a state that the pin holes 19 and 20 thereof correspond to each other as shown in the figure, and the brackets are overlapped inside and outside having the brackets 16 and 18 on the inner side, and connected to each other by a pin connection device 21 provided between the brackets 16 and 18 on the inner side.
Hereinafter, the brackets 16 and 18 are referred to as the inner brackets and the brackets 15 and 17 are referred to as the outer brackets, according to need.
The pin connection device 21 is provided with a first pin 22 for connecting the first brackets 15 and 16 to each other and a second pin 23 for connecting the second brackets 17 and 18 to each other. Both the pins 22 and 23 perform the stroke operation in the opposite direction to each other so as to be inserted into and removed from the pin holes 19 and 20 on the both sides.
FIG. 11 respectively shows a pin insertion state on the right side and a pin removal state on the left side with respect to a center line. Hereinafter, a pin position on the right side of FIG. 11 is referred to as an insertion position and a pin position on the left side is referred to as a removal position, according to need.
Both the first and second pins 22 and 23 are respectively driven by hydraulic cylinders 24. Both the hydraulic cylinders 24 have all the same configuration. Therefore, a description regarding to the cylinder configuration will basically be given only for one side hereinafter, and a separate description will be added for each of the cylinders according to need.
The pins 22 and 23 are integrated with cylinder tubes of the hydraulic cylinders 24. The hydraulic cylinders 24 are formed by the pins 22 and 23, pistons 25 and hollow piston rods (hereinafter, simply referred to as rods) 26 connected to the pistons 25 and extended and contracted by an oil supply and discharge effect from the exterior so that the pins 22 and 23 perform the stroke operation between both the insertion and removal positions.
Both the hydraulic cylinders 24 are formed as separately independent cylinders in which the rods 26 are divided at a center part of the device. Both the cylinders 24 are arranged in series in a state that rod ends thereof opposing to each other support reaction force on the extending side for each other.
Specifically, in the rod ends of both the cylinders 24, reaction force transmitting portions 27 in a circular shape are provided projectingly to the outer peripheral side. Since abutment surfaces 27a serving as surfaces of both the reaction force transmitting portions 27 opposing to each other are brought into abutment with each other in the rod axial direction. Therefore, the reaction force on the cylinder extending side is supported on the respective rod ends.
Meanwhile, on the outer peripheral sides of both the pins 22 and 23, cylindrical pin guide members 28 are provided so that the pins 22 and 23 are retained horizontally and perform the stroke operation between the insertion position and the removal position.
In the pin guide members 28, outer collar portions 28a provided in outer ends thereof are fixed to and cantilevered by the inner brackets 16 and 18. To inner ends (inner collar portions 28b) serving as free ends of the pin guide members 28, supporting plates 29 for receiving reaction force on the cylinder contracting side are attached.
The supporting plate 29 is formed in a half-divided shape with ring bodies 29a and 29b formed in a semicircular shape so as to be attached and detached between the pin guide members 28 on the both sides from the outside in the pin radial direction as shown in FIG. 12.
In a state that the inner peripheral side of the plate 29 is convexly and concavely engaged with an engagement portion 27b provided in an outer peripheral part of an opposite surface to the abutment surface 27a in the reaction force transmitting portion 27, an outer edge part of the above plate 29 is detachably attached to the inner collar portion 28b of the pin guide member 28 by bolts 30.
Thereby, the reaction force on the cylinder contracting side at the time of pin removal is transmitted from the reaction force transmitting portion 27 to the supporting plate 29 and supported in the pin guide member 28.
Meanwhile, oil passages 31 and 32 on the extending side and the contracting side are respectively formed in an axial center part of the rod 26 in a tunnel shape extending in the rod axial direction. Both the oil passages 31 and 32 are linked to a pump circuit and a tank circuit through a pipe joint 33 provided between both the hydraulic cylinders 24 and an external pipe (not shown).
As mentioned above, supply and discharge of oil for the hydraulic cylinders 24 are performed via the rods.
According to the pin connection device 21, the entire length of the device is shortened. Therefore, even in the case where the boom width is narrow (a clearance between the brackets on the both sides is narrow), it is possible to assemble the device.
In the above prior art, the outer ends of the pin guide members 28 are attached to and cantilevered by the inner brackets 16 and 18 as mentioned above. However, there is a problem regarding to attachment of the pin guide members 28 as follows.
A description will be given taking the pin guide member 28 and the inner bracket 16 on the left side in the figure as an example. There is no problem when the outer end of the pin guide member 28 can directly be fixed to the bracket 16. However, since the clearance between the brackets is narrow, it is not possible to process screw holes or the like in the bracket 16.
Therefore, as shown in the figure, a bushing 34 is press fitted to the pin hole 19 of the bracket 16, and a flange 34a is press fitted to an outer periphery of the bushing 34. Then, an outer periphery of the flange 34a is welded to the bracket 16, and the outer collar portion 28a of the pin guide member 28 is fixed to the flange 34a by bolts 35.    Patent Document: Japanese Patent No. 3399960